Warts, or verrucae, are a common and troublesome occurrence of viral etiology. Their epidemiology is not well understood. In many cases partial or complete remission occurs over a period of months or years, however many cases refuse to resolve spontaneously.
The folklore concerning the etiology of warts is exceeded only by that relating to cures. Even recent credible medical publications report cures which are quite empirical and mysterious. For example, in the American Journal of Obstetrics & Gynecology, Vol. 116, p. 887, July 15, 1973, a doctor reports the cure of an extremely severe case of vulvar warts with hypnosis. Successful use of hypnosis in the treatment of warts, along with a literature review, is also reported by a group of doctors in Arch. Gen. Psychiatry, Vol. 2B, p 439ff, March 1972. An article in Practitioner, Vol 210, p 829, June 1973, prescribes exercises of the hip, lower leg, and foot for the cure of plantar warts. An article in Physical Therapy, Volume 53, p 396, April, 1973 summarizes the literature on treatment of plantar warts with ultrasound, and compares direct ultrasonic treatment with underwater ultrasonic treatment. The exposure of warts to x-rays in a well-known attempted cure, although serious radiation damage is a risk as reported by the Singapore Medical Journal, Vol 14, No 1, p 19, March, 1973.
Plantar warts, so characterized because they are found on the sole of the foot, are particularly painful and stubborn, and are the subject of many cure efforts. The successful surgical removal of plantar warts with a blunt instrument is described in Archives of Dermatology, Vol 108, p 79, July, 1973. An interesting procedure for treating recalcitrant plantar warts by sensitization of the patient to dinitrochlorobenzene, followed by topical treatment of the wart with a dinitrochlorobenzene solution, is reported in Journal of the American Podiatry Association, Vol 63, No 7, p 293, July, 1973. Other well-known methods for treating warts include curretage, dessication, electric cutting, freezing with carbon dioxide or liquid nitrogen, and treatment with salicylic acid, podophyllin resin, formaldehyde, bichloracetic acid, silver nitrate, linseed oil, and cantharidin.
Despite substantial effort, a satisfactory cure for warts has not been found. Although some of the treatments mentioned above are statistically quite effective, none are completely effective, and many are painful, dangerous and leave unaceptable scars. In addition, even after removal by these methods, warts frequently recur at original or new sites and must be retreated.
The treatment of the invention involves the injection of procaine directly into and under a wart. Procaine is the diethylaminoethyl ester of para-aminobenzoic acid, and has the following formula: ##STR1## Sold under the trade names of Novocain, Ethocaine, and Neocaine, a solution of the hydrochloride salt of procaine has been sold for many years as a local anesthetic, and has achieved wide use. Procaine is a white crystalline powder, slightly soluble in water, melting at about 60.degree. C. The hydrochloride salt, however, is freely water-soluble. The solution is sold as a 2% solution of procaine in water, generally with a small amount of vasoconstrictor, with sufficient strong acid (usually HCl) added to reduce the solution pH to between 4 and 5. The salt procaine hydrocloride is formed at this pH, but readily dissociates at pH above 7. When the solution is injected into alkaline tissues, the alkaloidal base is liberated and penetrates the nerve fibers, causing anesthesia. Although a relatively weak anesthetic, procaine has a long history of safe use, and is essentially systemically non-toxic, being readily hydrolyzed in the tissues and detoxified in the liver. Amounts to 20 cc of the 2% procaine solution are commonly used in dentistry without ill effects. In recent years, procaine has been used in combination with other anesthetics, such as provocaine (2 diethylaminoethyl 4-aminopropoxylbenzonate) or tetracaine (p-butylaminobenzoyl-dimethylaminoethanol hydrochloride) for increased potency.
Although primarily known as an injected anesthetic, procaine has been reported to be useful for other related and non-related purposes. For example, McCrea, U.S. Pat. No. 2,105,197, issued Jan. 11, 1938, discloses the use of procaine as a topical anesthetic to reduce itching sensation. Dekker, U.S. Pat. No. 3,175,941, issued Mar. 30, 1965 shows procaine to be an active fungicide against powdery mildew on plants. Tulek, U.S. Pat. No. 2,539,848, issued Jan. 30, 1951 uses procaine as a raw material for the manufacture of procaine urea salicylate, useful in treating ulcers. In addition, recent newspaper articles have reported procaine-based drugs to be useful for anti-depressant and anti-aging activity in humans.